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Confronting uncertainties in a freshwater recreational fishery : a case study of fluvial bull trout (Salvelinus confluentus) in central British Columbia Chudnow, Rachel Elizabeth


Recreational fishery managers operate within complex socio-ecological systems and must balance objectives relating to resource conservation and human use opportunities. Further, agencies have limited resources and often lack high quality ecological and social data to inform decision making. As a result, managers confront considerable uncertainty when faced with management decisions and consequently, recreational fisheries are generally managed passively and/or reactively. This dissertation addresses several management challenges within a recreational bull trout fishery in the upper Fraser River watershed of British Columbia (UFW) by clarifying uncertainties related to population productivity, fish movement, and the responses of fish and human populations to changing fishery regulations. First, I develop a hierarchical Bayesian meta-analysis to provide the first bull trout specific estimate of recruitment compensation. Second, I use telemetry and genetic assignment data through state-space capture-recapture modeling to estimate seasonal movement patterns for multiple bull trout populations in the UFW. Finally, I use compensation and movement estimates from the first two models to develop a population dynamics model and decision analysis for a bull trout population complex in the UFW. Stock-recruitment model results indicate bull trout have strong potential for compensatory improvements in juvenile survival when population abundance is reduced, although there is considerable uncertainty in these estimates. This finding suggests habitat quality and quantity likely limit bull trout recovery for many populations across the species range. Movement modeling demonstrates that multiple spawning populations of fluvial bull trout utilize habitats within the UFW in a similar way, using a shared migratory corridor to access favourable spawning, wintering, and foraging habitats. The population dynamics model and decision analysis predict that changing management regulations to permit a low level of retention improves angler satisfaction without measurable impacts on the fishery’s conservation objective. However, even under current catch-and-release regulations, the model predicts populations are close to an overfished state. Results and conclusions developed here provide an important management tool within the UFW. Taken separately or together, these models can also reduce uncertainties and improve management decision making for other recreational fisheries both within British Columbia, or more broadly, where data limitations prevent other approaches from being applicable.

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